Fluid is defined as a continuous, amorphous substance where molecules move freely past one another and that has the tendency to assume the shape of its container. Many substances are fluids including but not limited to water. For purposes of this patent disclosure the fluid is described as being water but it is to be expressly understood the fluids described herein are not limited to water. Water at the molecular level is formed of two Hydrogen (H) atoms bonded to one Oxygen (O) atom. The chemical formula for water is H2O. Water is one of the most abundant substances on Earth and is essential for animal life and plant life. Most life and particularly animal life requires water that is free from contaminants and more particularly free from harmful contaminants. There are a variety of known processes for separating contaminants from water, and such processes may be as simple as a screen filter and as complex as reverse osmosis. Generally it is the type of contaminant that is to be removed from the water, and the subsequent use of the water that dictates the complexity of the process used to remove the contaminants. For example, if human consumption (potable water) is the desired end product, the system/process must remove all harmful contaminants and such systems can be both complex and expensive. Conversely, if the desired end product is water suitable for industrial purposes, the system may not need to be so complex, robust and expensive.
One industrial process that produces large volumes of contaminated fluid as a byproduct is induced hydraulic fracturing. Induced hydraulic fracturing or hydro-fracturing, sometimes termed “fracking”, is a technique in which water is mixed with sand and chemicals, and the mixture is injected at high-pressure into a well bore to create small fractures (typically less than 1 mm), along which desirable fluids including gas, petroleum and hydrocarbons may migrate to the well for collection and harvesting.
The hydraulic fractures are created by pumping fracturing fluid into the well bore at a rate sufficient to increase down-hole pressure above the fracture gradient (pressure gradient) of the rock. The rock cracks and the fracturing fluid continues propagating into the rock, extending the crack still further. Introducing a proppant, such as grains of sand, ceramic, or other particulates into the fracturing fluid prevents the fractures from closing upon themselves when the pressure of the fluid is removed.
During the fracturing process, some amount of fracturing fluid is lost through “leak-off” when the fracturing fluid permeates into the surrounding rock. If not adequately controlled, fracturing fluid leak off can exceed 70% of the injected volume. The portion of the fracturing fluid that is not lost through “leak off” returns to the surface through the well and is called “waste water”, “flow back water” or “produced water”. The waste water may be heavily contaminated.
Hydraulic fracturing equipment usually consists of a slurry blender and one or more high-pressure high-volume fracturing pumps, a monitoring unit and associated equipment including, but not limited to, fracturing fluid tanks, units for the storage and handling of proppant, a variety of testing, metering and flow rate equipment and storage tanks and/or ponds for contaminated waste water. Typically, fracturing equipment operates in high-pressure ranges up to approximately 15,000 psi and at volume rates of approximately 9.4 ft.3 per second. This is approximately 100 barrels fluid per minute at 42 gallons per barrel. (4200 gallons per minute).
The fracturing fluid injected into the well is typically a slurry of water, proppants, poly-coagulants and chemical additives comprising approximately 90% water, approximately 9.5% sand and approximately 0.5% chemical additives. A typical fracturing fluid composition, many of which are proprietary and considered industrial trade secrets, uses between three (3) and twelve (12) chemical additives which may include: acids, sodium chloride, poly acrylamide, ethylene glycol, sodium carbonate, potassium carbonate, flutaraldehyde, guar gum, citric acid and isopropanol. Some portion of the additives maybe charged particulates and/or ionic molecules.
A typical fracturing process requires between approximately two million and five million gallons of water per well. Approximately 10%-40% of the fracturing fluid pumped into the well returns to the surface as wastewater and commonly contains a variety of contaminants including, but not limited to, hydrocarbons, carbon dioxide, hydrogen sulphide, nitrogen, helium, iron, manganese, mercury, arsenic, lead, particulates, chemicals and salts as well as the chemical additives added to the fracturing fluid before injection into the well. Wastewater production commonly averages between approximately 3,000 barrels and 5,000 barrels per day at 42 gallons per barrel. (126,000-210,000 gallons).
The wastewater flowing back to the surface and exiting the well bore is collected and pumped into wastewater storage tanks or into wastewater ponds that are lined with plastic or the like to prevent the wastewater from leaching into the ground. After the fracking operation is complete, the wastewater storage tanks and/or wastewater storage ponds are drained and the wastewater therein is transported to salt water dumps (SWDs) or hazardous waste sites for permanent disposal.
Beginning in 2015, a United States Government Environmental Protection Agency (EPA) regulation will require a “paper-trail” that documents when and where all hydraulic fracturing wastewater originates and where the wastewater is taken for disposal. These new regulations create additional expenses and increase future potential liabilities of drillers and fracking operators.
In the Marcellus Shale deposit of North Dakota USA, it is estimated to cost more than approximately $3 per barrel (42 gallons/158.98 liters) to dispose the wastewater and approximately $7 to $10/per barrel (42 gallons/158.98 liters) to transport wastewater to an approved disposal site. There is also a cost for sweet water (fresh water) needed for conducting the hydraulic fracturing operation. In arid and semi-arid areas fresh water is an additional cost factor. For example the hydraulic fracturing of a horizontal well may use approximately 4.2 million gallons (15.89 million liters) of fresh water which must be purchased and available for the fracking operation.
Fresh water sourcing is becoming a revenue business as some municipalities and landowners in the Western United States are selling water rights to the petroleum drilling industry for hydraulic fracturing.
For example, Texas has small amounts of available fresh water but has the geography to properly dispose of contaminated wastewater. Pennsylvania, on the other hand, has abundant supplies of fresh water but has no place to dispose of wastewater. In the Northeast United States, disposal of wastewater is problematic and as a result wastewater disposal has moved generally West toward Ohio and Indiana and Virginia where the wastewater is being dumped into pits. It is estimated in the near future, wastewater “dumpers” may have to pay as much as approximately $5,000 to $6,000 per truckload in disposal site charges not including the cost of transporting the waste water to the dump site.
There are four primary methods for dealing with hydraulic fracturing wastewater. A first method reuses the untreated wastewater in the hydraulic fracturing process. Unfortunately, reuse is problematic as high levels of contaminants tend to plug the well with “residual chemicals”, particulates, or shale fines” which may negatively impact production of the well.
A second method is “deep well injection,” which entails drilling a deep disposal well into which the wastewater is pumped for permanent disposal. Deep well injection is problematic as seismologists and the scientific community have alleged earthquakes “were almost certainly induced by the disposal of fracking wastewater in deep disposal wells.” The drilling of a disposal well is also expensive and such disposal increases the volume of fresh water required for fracturing operations as the wastewater is not re-used.
A third method is on-site treatment of the wastewater which removes the most harmful chemicals and contaminants from the wastewater. Some portion of the treated water may then be reused in the fracturing. On-site treatment generally has negligible transportation costs, but with known systems and known technology is more expensive than other options due to the high maintenance costs of known systems and the need to repeatedly shut the system down for cleaning and backwashing. Further, such known systems and technology operate under high pressures typically exceeding 250 psi, are readily known for being easily damaged and even destroyed by small amounts of hydrocarbons that may accidentally pass through the system to filter membranes. Such filter membranes have a limited amount of membrane surface area available for filtration, are expensive, and difficult to replace. Further, membrane replacement is a time consuming process during which the system must be shut down.
The fourth method is off-site treatment and disposal of the wastewater. Similar to deep well injection, off site treatment and disposal increases the volume of fresh water required for fracturing operations as the wastewater is not reused or recycled. This fourth option is the most expensive as transportation costs and disposal costs may be enormous.
One industry estimate places the cost of treating wastewater, including costs for equipment, operation, labor, chemicals, and sludge handling, at up to approximately $20 per barrel. Because hydraulic fracturing may produce upwards of 3,000-5,000 barrels (126,000-210,000 gallons, or 476,961-794,936 liters) of wastewater per well, per day, this cost may be as high as $60,000-$100,000 per day.
The huge volume of fresh water necessary for fracturing operations, many of which occur in arid and semiarid areas, is another significant cost that must be recouped. Any ability to reuse or recycle wastewater can offset some portion of the cost. Water, be it the acquisition of fresh water, the handling of the wastewater, and the ultimate disposal of the wastewater is a significant and burdensome cost that is necessarily borne in the cost of the well. Further, because the wastewater may be so contaminated with pollutants, chemicals, salts and the like, the wastewater may be characterized as “hazardous waste” that must be inventoried, tracked, and handled with extreme care prior to, during and after disposal. Further, disposal of “hazardous waste” leads to more hazardous waste sites that permanently damage the environment.
Any means by which wastewater may be filtered or otherwise treated to remove contaminants and allow reuse and/or recycling of the water, or disposal of the water in sites other than “hazardous waste sites” or “saltwater dumps” will reduce the cost of bringing wells into production and will reduce the hazardous byproducts and environmental impacts of hydraulic fracturing operations.
The instant improved contaminant removal system resolves various of these known problems by providing a mobile truck mounted system comprising a combination of known and new filtration and separator technology and salt removal technology for wastewater generated as a byproduct of hydraulic fracturing operations, wastewater from industrial processes and wastewater from agricultural operations, including, but not limited to feedlots.
The instant improved contaminant removal system allows the wastewater to be recycled for re-use by separating and removing contaminants in a series of steps which provides savings by reducing the need for fresh water and reducing costs of transportation to and from fresh water sources, reducing the need to transport wastewater to dump sites, reduction in dump fees and by reducing the amount of wastewater that requires governmental regulated disposal.
The removal of contaminants, including but not limited to solids, oils, BTEX compounds, diesel, benzene, toluene, xylene, ethyl-benzene, distillates, dissolved salts, phosphates, iron, manganese, arsenic, poly-coagulants, fertilizers and animal waste is achieved through use of the instant improved contaminant removal system.
The instant improved contaminant removal system is modular and is carried on trailers allowing the entire system to be mobile. The kilowatt (KW) requirement for the complete system is approximately 500 KW which may be supplied by portable skid mounted generator sets.
The performance of the instant improved contaminant removal system provides for removal of contaminants and recovery of the fluid between approximately 350 gallons per minute (GPM) and approximately 450 GPM.
The instant improved contaminant removal system removes even small amounts of hydrocarbons that destroy Poly-Pan filtration membranes of salt removal systems which are costly to repair, replace and maintain.
The instant improved contaminant removal system uses a novel electrocoagulator system to avoid or at least minimize the need for chemical coagulants and precipitates which increase the number of contaminants to be removed from the fluid and ultimately disposed.
The instant improved contaminant removal system's novel electrocoagulator system is not affected by temperature of the fluids being filtered and as a result can be used in a wider variety of circumstances and conditions and is not dependent upon chemical reactions.
The instant improved contaminant removal system uses a novel electrocoagulator system with plural replaceable concentrically aligned perforated anodes and cathodes that are closely spaced adjacent one another so that the energy requirements for powering electrocoagulation is minimized.
The instant improved contaminant removal system's use of plural concentrically aligned replaceable perforated anodes and cathodes provides a greater surface area for electrocoagulation to occur and the perforation of the anodes and cathodes has negligible affect on the pressure and flow of fluids through the system.
The instant improved contaminant removal system's plural concentrically aligned anodes and cathodes release ions into the fluid, and as the ionic charges of the contaminants is neutralized or reduced by bonding with the released ions, emulsions, colloids and ionically charged particles agglomerate and rise to the surface of the fluid with the microbubbles forming a flocculent on the surface of the fluid which is removed by the swiper blades of the removable top.
The instant improved contaminant removal system's electrocoagulation is not affected by hydrocarbons. Copy removes hydrocarbon emulsions and colloids from the fluid.
Some or all of the problems, difficulties and drawbacks identified above and other problems, difficulties, and drawbacks may be helped or solved by the instant improved contaminant removal system shown and described herein. The instant improved contaminant removal system may also be used to address other problems, difficulties, and drawbacks not set out above or which are only understood or appreciated at a later time. The future may also bring to light currently unknown or unrecognized benefits which may be appreciated, or more fully appreciated, in the future associated with the novel inventions shown and described herein.